Nine Virgin Australia planes have been caught up in a worldwide aviation alert over faulty bolts that hold the aircraft's engines in place.

The faults on Embraer 190 planes were first discovered by Virgin's heavy maintenance crews on Wednesday, prompting the Brazilian manufacturer to issue an ''alert service bulletin'' to all airlines operating the aircraft.

The issue relates to bolts that hold the engine onto the engine pylon, which is attached to the plane's wing.

A full inspection of its fleet of 17 Embraer 190 aircraft found faults with nine of them, which were grounded while repairs were carried out.

''These aircraft have since undergone the necessary precautionary repairs and have since returned to service,'' a Virgin Australia spokesman told Fairfax Media on Friday.

''The safety of our aircraft is our highest priority and we have been in regular dialogue with Embraer regarding this alert.''

The Civil Aviation Safety Authority has been informed about the alert, a spokesman said.

The Embraer 190 is slightly smaller than a Boeing 737 and is used by the airline to service regional and metro routes across the country, including Brisbane to Sydney, as well flights to Christmas Island and the Cocos Islands.